1. Field of the Invention
The present invention relates to a developing device or a process cartridge which is used in an electrophotographic image forming apparatus such as an electrophotographic copier, an electrophotographic printer or the like, and an electrophotographic image forming apparatus which uses the developing device or the process cartridge, for example.
Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming process. Examples of electrophotographic image forming apparatus include an electrophotographic copier, an electrophotographic printer (an LED printer, a laser beam printer or the like), an electrophotographic facsimile device, an electrophotographic word processor and the like.
Here, the process cartridge is an assembled body formed by integrally forming at least a developing means and an electrophotographic photosensitive member into a cartridge and this cartridge can be replaceably mounted on or dismounted from an image forming apparatus body.
2. Description of the Related Art
Conventionally, there has been adopted a process cartridge system in which a photosensitive drum, charging means, developing means, cleaning means and the like are integrally formed into a cartridge and the cartridge is replaceably mounted on or dismounted from an apparatus body of an image forming apparatus.
Thanks to this cartridge system, the operability is further enhanced so that the maintenance of the above-mentioned process means such as the charging means, the developing means, the cleaning means and the like can be easily performed by a user himself. Accordingly, this cartridge system has been popularly used in the apparatus body of the image forming apparatus.
Further, there has been also realized a cartridge constitution in which the process means is classified into process means having a long life time and a process means having a short life time and these respective process means are formed into cartridges and can be used in accordance with the life time of the main process means. For example, a developing cartridge in which a toner accommodating portion and the developing means are integrally formed, a drum cartridge in which the photosensitive drum, the charging means and the cleaning means are integrally formed and the like are adopted.
In such a cartridge-type image forming apparatus, as a developing method which has been conventionally used, a so-called magnetic brush developing method has been known. In this magnetic brushing method, using a two component developer consisting of non-magnetic toner and a magnetic carrier, a magnetic brush is formed on a surface of a developer bearing member (also referred to as a developing sleeve hereinafter) which arranges a magnet in the inside thereof. Then, this magnetic brush is brought into slidable and frictional contact with or is arranged in the vicinity of the photosensitive drum which is arranged to face the developing sleeve in an opposed manner while maintaining a minute developing gap therebetween. Subsequently, an electric field is continuously applied between the developing sleeve and the photosensitive drum. Accordingly, the developing is performed by repeatedly performing the transfer of the toner particle from the developing sleeve side to the photosensitive drum side and the inverse transfer of such toner particles.
Here, in this magnetic brush developing method, the non-magnetic toner and the magnetic carrier are agitated and are transported by a screw and are eventually supplied to the developing sleeve. Such a constitution has been conventionally popularly adopted.
Recently, along with the demand for high speed operation of a printer, not to mention the peripheral speed of the photosensitive drum, the peripheral speed of the developing sleeve in the inside of the developing device is increased, thus giving rise to the elevation of the internal pressure and the occurrence of an air flow in the inside of the developing device.
There exists a possibility that the developer scatters through a minute gap due to these phenomena. The scattering of the developer smears in the inside of the process cartridge, a scanner and the electrophotographic image forming apparatus including the developing device.
Accordingly, it is an object of the present invention to provide a developing device, a process cartridge and an electrophotographic image forming apparatus which can prevent leaking of a developer.
It is another object of the present invention to provide a developing device, a process cartridge and an electrophotographic image forming apparatus which can prevent scattering of a developer into an exposure optical path which may be caused by leaking of the developer.
It is still another object of the present invention to provide a developing device, a process cartridge and an electrophotographic image forming apparatus which can prevent the elevation of the internal pressure in the inside of a developer containing portion.
It is a further object of the present invention to provide a developing device for developing a latent image formed on an electrophotographic photosensitive member used in an electrophotographic image forming apparatus, wherein the developing device includes a developing member for developing the latent image formed on the electrophotographic photosensitive member, an exposure optical path for guiding an exposure light emitted from exposure means mounted in a body of the electrophotographic image forming apparatus to the electrophotographic photosensitive member, a developer containing portion for containing a developer which is used by the developing member for developing the latent image, a vent port for allowing air in the inside of the developer containing portion to pass therethrough, a first sheet member for preventing scattering of the developer into the exposure optical path, the first sheet member being disposed between the exposure optical path and the developing member and being in contact with the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, a first sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the first sealing member being in contact with one end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and a second sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the second sealing member being in contact with another end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member.
It is a still further object of the present invention to provide a process cartridge which is detachably attachably mounted on a body of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive member, a developing member for developing the latent image formed on the electrophotographic photosensitive member, an exposure optical path for guiding an exposure light emitted from exposure means mounted in a body of the electrophotographic image forming apparatus to the electrophotographic photosensitive member, a developer containing portion for containing a developer which is used by the developing member for developing the latent image, a vent port for allowing air in the inside of the developer containing portion to pass therethrough, a first sheet member for preventing scattering of the developer into the exposure optical path, the first sheet member being disposed between the exposure optical path and the developing member and being in contact with the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, a first sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the first sealing member being in contact with one end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and a second sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the second sealing member being in contact with another end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member.
It is a still further object of the present invention to provide an electrophotographic image forming apparatus for forming an image on a recording medium, wherein the electrophotographic image forming apparatus includes (a) exposure means, (b) a developing device for developing a latent image formed on an electrophotographic photosensitive member used in the electrophotographic image forming apparatus, the developing device including a developing member for developing the latent image formed on the electrophotographic photosensitive member, an exposure optical path for guiding an exposure light emitted from exposure means mounted in a body of the electrophotographic image forming apparatus to the electrophotographic photosensitive member, a developer containing portion for containing a developer which is used by the developing member for developing the latent image, a vent port for allowing air in the inside of the developer containing portion to pass therethrough, a first sheet member for preventing scattering of the developer into the exposure optical path, the first sheet member being disposed between the exposure optical path and the developing member and being in contact with the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, a first sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the first sealing member being in contact with one end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and a second sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the second sealing member being in contact with another end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and (c) conveying means for conveying the recording medium.
It is another object of the present invention to provide an electrophotographic image forming apparatus for forming an image on a recording medium on which a process cartridge can be detachably attachably mounted, wherein the electrophotographic image forming apparatus includes (a) exposure means, (b) mounting means for detachably mounting the process cartridge which includes an electrophotographic photosensitive member, a developing member for developing the latent image formed on the electrophotographic photosensitive member an exposure optical path for guiding an exposure light emitted from exposure means mounted in a body of the electrophotographic image forming apparatus to the electrophotographic photosensitive member, a developer containing portion for containing a developer which is used by the developing member for developing the latent image, a vent port for allowing air in the inside of the developer containing portion to pass therethrough, a first sheet member for preventing scattering of the developer into the exposure optical path, the first sheet member being disposed between the exposure optical path and the developing member and being in contact with the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, a first sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the first sealing member being in contact with one end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and a second sealing member for preventing leaking of the developer in the inside of the developer containing portion from the developer containing portion, the second sealing member being in contact with another end portion of the electrophotographic photosensitive member in the longitudinal direction of the electrophotographic photosensitive member, and (c) conveying means for conveying the recording medium.
These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.